Analysis of subjective acoustic measures and speech intelligibility in Portuguese churches.

Abstract

This study reports on subjective acoustical field measurements made in a survey of 36 Catholic churches in Portugal built in the last 14 centuries. The same group of college students were asked to judge the quality of speech and music at all the churches. Two sets of listeners in each church evaluated live music performance (cello and oboe) at two similar locations in each of the rooms using a seven-point semantic differential rating scale. An acoustical evaluation sheet was used to measure listeners overall impression of room acoustics qualities, and each of the factors that can contribute to that perception as loudness, reverberance, intimacy, envelopment, directionality, balance, clarity, echoes and background noise. Speech intelligibility tests were also given to the same group in each church. One-hundred-word lists were used in live speech tests using a theater college student as speaker. The results are graphed and analyzed by comparisons. Variations of subjective and speech intelligibility qualities were identified among the different churches and within each of the churches as well. The subjective qualities that contributed to overall acoustical impression were also identified. -INTRODUCTIONThis study is part of a research program initiated in 1991 by the author at the University of Porto and University of Florida. The aim of the project is to explore methods to evaluate, predict and preview the acoustical qualities of churches. The program has included two major components to date:• Objective studies of existing churches -Measurements were taken in 41 Portuguese Catholic churches, at multiple locations in each room. Several objective acoustical parameters were measured (RT, EDT, C80, D50, TS, L, BR_RT, BR_L, RASTI) (Carvalho 1994).• Subjective studies of existing churches -This has included both evaluating live musical performances in 36 churches and speech intelligibility testing. This work is characterized by the use of a sample of listeners, evaluation of several locations in each room, assessment of many rooms and comprehensive statistical analysis of the data.This paper presents a preparatory report regarding the second item. More complete analysis of the data gathered is been prepared. A paper in the continuation of this work is expected to be presented at the 132nd Meeting of the Acoustical Society of America in Honolulu, concerning relationships between objective and subjective acoustical parameters found in this large sample of churches. -METHODOLOGY -Method SummaryThe main research hypothesis is that the perceptions of people who attend services or concerts in churches could be measured. The among-room variations of subjective scores can be viewed as differences that result from the architectural and acoustical proprieties of the churches that experience shows actually exist. Therefore strategies to measure and predict these variations would be helpful to acoustical consultants and architects.The study consisted of two parts both regarding subjective analyses in almost non occupied ch...